Basis of Presentation and Significant Accounting Policies	6 Months Ended
Jul. 02, 2011
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Basis of Presentation and Significant Accounting Policies: The accompanying Condensed Consolidated Financial Statements are unaudited and have been prepared by Lattice Semiconductor Corporation (the “Company”, “we”, “us” or “our”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and in our opinion include all adjustments, consisting of normal recurring adjustments, necessary for the fair statement of results for the interim periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. These Condensed Consolidated Financial Statements should be read in conjunction with our audited financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended January 1, 2011. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts and classification of assets, such as marketable securities, accounts receivable, inventory, auction rate securities, deferred income taxes and liabilities, accrued expenses (including restructuring charges and accrual for bonus arrangements), income taxes, deferred income and allowances on sales to certain sell-through distributors, forward exchange contracts, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the fiscal periods presented. Actual results could differ from these estimates. We report based on a 52 or 53-week fiscal year ending on the Saturday closest to December 31. Our second quarter of fiscal 2011 and second quarter of fiscal 2010 ended on July 2, 2011 and July 3, 2010, respectively. All references to quarterly or three and six months ended financial results are references to the results for the relevant fiscal period. Cash Equivalents and Marketable Securities We consider all investments that are readily convertible into cash and have original maturities of three months or less, to be cash equivalents. Cash equivalents consist primarily of highly liquid investments in time deposits or money market accounts and are carried at cost. We account for marketable securities as available for sale with unrealized gains or losses recorded as Accumulated other comprehensive income, unless losses are considered other-than-temporary, in which case, losses are charged to the Condensed Consolidated Statements of Operations. Derivative Financial Instruments We have international subsidiary and branch operations. A portion of our silicon wafer and other purchases are denominated in Japanese yen and we bill our Japanese customers in yen. We mitigate the resulting foreign currency exchange rate exposure by entering into foreign currency forward exchange contracts for Japanese yen. Although such hedges mitigate our foreign currency exchange rate exposure from an economic perspective they were not designated as "effective" hedges for accounting purposes and are adjusted to fair value through Net income. We do not hold or issue derivative financial instruments for trading or speculative purposes. Concentration Risk Potential exposure to concentration risk consists primarily of cash and cash equivalents, marketable securities, trade receivables and supply of wafers for our new products. We place our investments primarily through four financial institutions and mitigate the concentration of credit risk by placing percentage limits on the maximum portion of the investment portfolio which may be invested in any one investment instrument. The Company's investment policy defines approved credit ratings for investment securities. Investments consisted primarily of money market instruments, “AA” or better corporate notes and bonds, “AA” or better rated U.S. municipal notes, and U.S. government agency obligations. See Note 5 for a discussion of the liquidity attributes of our marketable securities. Concentration of credit risk with respect to trade receivables is mitigated by a diverse customer base and our credit and collection process. Accounts receivable are recorded at the invoice amount, do not bear interest, and are shown net of allowances for doubtful accounts of $0.9 million at both July 2, 2011 and January 1, 2011. We perform credit evaluations for essentially all customers and secure transactions with letters of credit or advance payments where appropriate. We regularly review our allowance for doubtful accounts and the aging of our accounts receivable. Write-offs for uncollected trade receivables have not been significant to date. We rely on Fujitsu Limited ("Fujitsu") for essentially all wafer purchases for our new products. Revenue Recognition and Deferred Income Revenue from sales to customers is recognized upon shipment, or in the case of sales by our sell-through distributors, at the time of reported resale, provided that persuasive evidence of an arrangement exists, the price is fixed or determinable, title has transferred, collection of resulting receivables is reasonably assured, there are no remaining customer acceptance requirements and no remaining significant obligations. We sell our products directly to end customers or through a network of independent manufacturers' representatives and indirectly through a network of independent sell-in and sell-through distributors. Distributors provide us periodic data regarding the product, price, quantity and end customer when products are resold as well as the quantities of our products they still have in stock. We must use estimates and apply judgment to reconcile sell-through distributors' reported inventories to their activities. Any differences between our estimates and actual results could lead to inaccurate reporting of our Revenue, Cost of products sold, Deferred income and allowances on sales to sell-through distributors, and Net income. At the time of shipment to a sell-through distributor amounts are invoiced at published list price. The final price is set at the time of resale and is determined in accordance with a distributor price agreement. Amounts invoiced are recorded in Accounts receivable, net and inventory is transferred from Inventories to Deferred income and allowances on sales to sell-through distributors. Revenue and cost of products sold to sell-through distributors are deferred until either the product is resold by the distributor or, in certain cases, return privileges terminate, at which time Revenue and Cost of products sold are reflected in Net income. Our estimate of inventory valued at published list price and held by sell-through distributors with right of return totaled $48.5 million and $50.1 million at July 2, 2011 and January 1, 2011, respectively. Distributor advances totaled $24.7 million and $26.8 million at July 2, 2011 and January 1, 2011, respectively, and are recorded in Deferred income and allowances to sell-through distributors. Deferred costs of sales related to inventory held by sell-through distributors totaled $7.3 million and $7.6 million at July 2, 2011 and January 1, 2011, respectively. We expect the majority of our revenue in fiscal 2011 will be from reported resale from our sell-through distributors. Resale of product by sell-through distributors as a percentage of our total revenue was 57% and 60% for the three and six months ended July 2, 2011, respectively, and 57% and 56% for the three and six months ended July 3, 2010, respectively. Revenue from software licensing was not material for the periods presented.

Basis of Presentation and Significant Accounting Policies:

The accompanying Condensed Consolidated Financial Statements are unaudited and have been prepared by Lattice Semiconductor Corporation (the “Company”, “we”, “us” or “our”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and in our opinion include all adjustments, consisting of normal recurring adjustments, necessary for the fair statement of results for the interim periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. These Condensed Consolidated Financial Statements should be read in conjunction with our audited financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended January 1, 2011.

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts and classification of assets, such as marketable securities, accounts receivable, inventory, auction rate securities, deferred income taxes and liabilities, accrued expenses (including restructuring charges and accrual for bonus arrangements), income taxes, deferred income and allowances on sales to certain sell-through distributors, forward exchange contracts, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the fiscal periods presented. Actual results could differ from these estimates.

We report based on a 52 or 53-week fiscal year ending on the Saturday closest to December 31. Our second quarter of fiscal 2011 and second quarter of fiscal 2010 ended on July 2, 2011 and July 3, 2010, respectively. All references to quarterly or three and six months ended financial results are references to the results for the relevant fiscal period.

Cash Equivalents and Marketable Securities

We consider all investments that are readily convertible into cash and have original maturities of three months or less, to be cash equivalents. Cash equivalents consist primarily of highly liquid investments in time deposits or money market accounts and are carried at cost. We account for marketable securities as available for sale with unrealized gains or losses recorded as Accumulated other comprehensive income, unless losses are considered other-than-temporary, in which case, losses are charged to the Condensed Consolidated Statements of Operations.

Derivative Financial Instruments

We have international subsidiary and branch operations. A portion of our silicon wafer and other purchases are denominated in Japanese yen and we bill our Japanese customers in yen. We mitigate the resulting foreign currency exchange rate exposure by entering into foreign currency forward exchange contracts for Japanese yen. Although such hedges mitigate our foreign currency exchange rate exposure from an economic perspective they were not designated as "effective" hedges for accounting purposes and are adjusted to fair value through Net income. We do not hold or issue derivative financial instruments for trading or speculative purposes.

Concentration Risk

Potential exposure to concentration risk consists primarily of cash and cash equivalents, marketable securities, trade receivables and supply of wafers for our new products. We place our investments primarily through four financial institutions and mitigate the concentration of credit risk by placing percentage limits on the maximum portion of the investment portfolio which may be invested in any one investment instrument. The Company's investment policy defines approved credit ratings for investment securities. Investments consisted primarily of money market instruments, “AA” or better corporate notes and bonds, “AA” or better rated U.S. municipal notes, and U.S. government agency obligations. See Note 5 for a discussion of the liquidity attributes of our marketable securities.

Concentration of credit risk with respect to trade receivables is mitigated by a diverse customer base and our credit and collection process. Accounts receivable are recorded at the invoice amount, do not bear interest, and are shown net of allowances for doubtful accounts of $0.9 million at both July 2, 2011 and January 1, 2011. We perform credit evaluations for essentially all customers and secure transactions with letters of credit or advance payments where appropriate. We regularly review our allowance for doubtful accounts and the aging of our accounts receivable. Write-offs for uncollected trade receivables have not been significant to date.

We rely on Fujitsu Limited ("Fujitsu") for essentially all wafer purchases for our new products.

Revenue Recognition and Deferred Income

Revenue from sales to customers is recognized upon shipment, or in the case of sales by our sell-through distributors, at the time of reported resale, provided that persuasive evidence of an arrangement exists, the price is fixed or determinable, title has transferred, collection of resulting receivables is reasonably assured, there are no remaining customer acceptance requirements and no remaining significant obligations. We sell our products directly to end customers or through a network of independent manufacturers' representatives and indirectly through a network of independent sell-in and sell-through distributors. Distributors provide us periodic data regarding the product, price, quantity and end customer when products are resold as well as the quantities of our products they still have in stock. We must use estimates and apply judgment to reconcile sell-through distributors' reported inventories to their activities. Any differences between our estimates and actual results could lead to inaccurate reporting of our Revenue, Cost of products sold, Deferred income and allowances on sales to sell-through distributors, and Net income.

At the time of shipment to a sell-through distributor amounts are invoiced at published list price. The final price is set at the time of resale and is determined in accordance with a distributor price agreement. Amounts invoiced are recorded in Accounts receivable, net and inventory is transferred from Inventories to Deferred income and allowances on sales to sell-through distributors. Revenue and cost of products sold to sell-through distributors are deferred until either the product is resold by the distributor or, in certain cases, return privileges terminate, at which time Revenue and Cost of products sold are reflected in Net income. Our estimate of inventory valued at published list price and held by sell-through distributors with right of return totaled $48.5 million and $50.1 million at July 2, 2011 and January 1, 2011, respectively. Distributor advances totaled $24.7 million and $26.8 million at July 2, 2011 and January 1, 2011, respectively, and are recorded in Deferred income and allowances to sell-through distributors. Deferred costs of sales related to inventory held by sell-through distributors totaled $7.3 million and $7.6 million at July 2, 2011 and January 1, 2011, respectively.

We expect the majority of our revenue in fiscal 2011 will be from reported resale from our sell-through distributors. Resale of product by sell-through distributors as a percentage of our total revenue was 57% and 60% for the three and six months ended July 2, 2011, respectively, and 57% and 56% for the three and six months ended July 3, 2010, respectively.

Revenue from software licensing was not material for the periods presented.